MIMO (Multiple In Multiple Out) Wireless Ethernet radio technology is one of the candidates for the new 802.11n standard. Even though official ratification of the standard is more than a year out and it isn't clear what the final standard will look like, Belkin just couldn't wait to jump on the "n" bandwagon. Belkin is calling their new products "Pre-N" which is based on technology from Airgo Networks' True MIMO technology. Note that Belkin is careful not to call this product pre-802.11n because the IEEE has told companies not to roll out products implying that they are going to be 802.11n-compliant before the standard is ratified. But the implication is clear.

Looking at Belkin's highlights of a Tolly Group report, there is an extreme gap in capability compared to the other products listed. However, are the claims of 800% wider coverage and 600% faster speed really accurate? According to my calculations based on the numbers shown in their own figures, I calculate that Belkin's pre-N product has approximately 416% more square feet coverage and is 318% faster than the next best candidate. I guess Belkin must have been comparing against the weakest candidate to get the higher numbers. One thing that did strike me as odd is that there is no way that the other products would normally operate at 5 mbits/sec. The only plausible explanation for this was that Belkin used long range statistics to their advantage where all their competitors have fallen to the 5 mbit/sec range while their Pre-N product hums along at 23 mbits/sec. This is a bit deceptive since it offers a very narrow view and doesn't compare close range throughput. Looking for more authoritative research, I checked with Tim Higgins at Tomsnetworking.com and he was already working on a new article "Do Extended-range WLAN technologies deliver?." The article offers detailed scientific plots showing actual throughput vs. distance. To sum it up, MIMO reigned supreme -- although no where near the 600% claims. Here is what the results show:>

Belkin pre-N MIMO technology was able to sustain an average throughput well above 40 mbits/sec inside a typical house. It does so by using a single channel in the 2.4 GHz 802.11 b/g band while the closest competitor based on Atheros XR (Extended Range) technology could only come close to MIMO technology when it eats up 2 of 3 scarce channels in the 2.4 GHz band.

In long-range tests, Atheros XR beat all existing records, but the MIMO product went even further -- it was able to extend out to 400 feet while still maintaining 15 mbits/sec, which is absolutely unheard of! There are some weaker 802.11g products that can barely maintain 15 mbits/sec at 10 feet let alone 400 feet.

One capability of MIMO that wasn't tested in Tim's article (will come later) is its ability to operate in 802.11n mode even while supporting 802.11b or 802.11g clients. If this is confirmed, it will solve one of the biggest problems with 802.11g where it gets dragged down to 802.11b by any active 802.11b device.

There's no question that Belkin's "Pre-N" products based on True MIMO break all the records for range and speed. However, be aware that there is no guarantee that the product will be upgradeable to the full 802.11n spec and you may be stuck with a nonstandard product. One thing for certain is that the future of 802.11n looks bright. Thanks for the article Tim!

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